Universal triangle-protractor



1. MAGlLL.

. UNIVERSAL TRIANGLEVPBOTBACIOR.

APPLICATION FILED APR. 2B, 19.19.

1,370,6Q5, Patend Mar. 8, 1921.

J. IVIAGILL.

UNIVERSAL TRIANGLE PROTRACTOR.

APPucATloN man maze, 1919.

1,370,605. Patented Mar. s, 1921.

2 SHEETS-SHEE 2.

EEE..

JOHN MAGILL, OF WOONSOCKET, RHODE ISLAND.

UNIVERSAL TRIANGLE-PROTRACTOR.

Specification of Letters Patent.

Patented Mar. S, 1921.

i Application filed April 28, 1919. Serial No. 293,216.,v

" all 'whom it may concern:

Be it known that I, JOHN MAGILL, a citizen of the United States, residing at Voonsocket, in the county of Providence and State or' Rhode Island, have invented a new and useful improvement in Universal Triangle-Protractors, of which the following is a specification.

This invention relates to certain new and useful improvements in a universal triangle protractor, and it has for its primary object to provide an improved geometrical instrument for measuring and easily reading the several functions of any angle within the circle without any calculations on the part of the user, thereby especially adapting the instrument for draftsmen, machinists,l designers, carpenters, surveyors, and many other workmen who have to do with the measurement of angles, as Well as the ruling or straight lines, in their *.focations.

Further, the invention resides in the improved st-ructural features tending to lessen the cost of manufacturing thevarious parts and their assembling and increasing the usefulness and utility of the triangle protractor.

Another object of the invention is to pro vide means for etect-ing a nicety of adjustment, even to the thousandth of an inch, without the employment of a Vernier', and a still further aim is to provide for an arrangement of parts whereby the effect of an inaccurate setting will show to va minimum on the work.

The invention also resides in the features of construction.y and the arrangements and combinations of part-s hereinafter described and claimed, reference being made to the accompanying drawings wherein Figure 1 is la plan view of the improved universal triangle protractor.

Fig. 2 is a transverse sectional view through the relatively fixed center or fulcrum for the hypotenuse or work bar, said view being taken on line 2 2 of Fig. 1.

Fig. 3 is a similar view on line 3 3 of Fig. 1 through the outer end of the work bar.

Fig. 4 is a detailed elevation of the fixed center or 'fulcruin f slide.

Fig. 9 is an edge view thereof, and

Fig. l() is a detailed view of the wedge lock for the slide.

The triangle protractor consists of three major parts, namely the base side o r arm l, the upright side or arm 2 and the hypotenuse or working bar 3. The sides or arms are joined or connected to form a right angle by corner bracket or plate 4 which has one arm 5 extended upwardly alongthe inner edge of the upright side 2 in alinement with a narrow strip 6 which is riveted to the side 2 to slightly overhang the said inner edge to form a ruling edge spaced off the work and also guide the adjacent end of the working bar. Secured to the opposite edge portion of side 2 is a secondstrip or spacer 7 defining with the iirst strip a groove 8 running lengthwise of the side and closed bythe bracket plate t at one end only.` Superposed on the spacer strip 7 is a keeper plate overhanging the groove and extending the full length of side 2, said keeper plate 9 being also secured to the underlying support by rivets as indicated.

Fixed on the outer end of the horizontal or base side 1 is a bracket plate 10 having its upper end deflected and equipped with a disk shaped bearing 11 constituting the iiXed center or pointotl fulcrum for the working bar 3. The body portion of the bracket is provided with a pair of horizontal slots 13 through which the shanks of a pair of adjusting screws lll are passed, said screws securing an overlying clamping plate 15 to the base side, as is illustrated in Fig. 2. A guide cleat 16 is secured transversely'across the underside of the Vbracket 10 to coact with the upper edgey of the side 1 in steadying said bracket. Y

Slidable in the groove 8 is a shoe 17vvhich is retained therein by the keeper plate 9, and secured to this shoe so as to guidingly abut the keeper plate is a slide member 18 that has a bearing formedtherein in which the hub 19 carried by one end of the w0rking bar 3 is journaled. The working bar Y comprises a long steel bar having an edge reinforcement 21 along its primary working edge, and adjacent its outer end the opposite edge is provided with a guide strip 22 spaced oil the side i'aceioi the working bar by means of transverse spacer blocks 23 disposed at each end. In proximity to the spacerblock at the extreme end of the work ing bar, the latter has a portion removed to form an entrance opening to the space between the bar and guide strip 22. u During the process of assembling the parts, the deiiected 'end portion of the fulcrum plate 10 is insertedY through the entrance opening 24 to slide in-'the slot between the bar andthe v guide strip 22, the bearing 11 operating in the s space between and against the strip and the reinforcing strip 21.

The two centers 11 and'19 are related so that when the slide 18 is in the lower end of groove 8 the working bar willbe horizontal and when the slide is moved to the upper end of the groove the bar will assume an angle of 45o. For ease in determining the guide Y adjustment or setting to be made, the keeper plate is provided with graduations 25 starting zero at the lower end of the groove, registering mark 26 'being noted on the slide 18. In measuring angles, the barl 21 is first moved to zero position-and placed on the base line or side of an angle, subsequent to which lsaid bar is adjusted to coincide with the other side of the angle and the readinv accordingly made. Thus,the use and rear in is positive and correct.

, en the slide has been properly set it is held by either Vor both of two locking devices,` the first consisting of an angular finger 27 ivotedpto'the slide for being sprung un er the overhanging ledge of vthe Akeeper plate, as depicted in. Fig. 1, and the second embodying a wedge action and conslsts of a block 28 slidable in the groovefS Vand provided with a dovetailed projection engaged in a similarly shaped recess or slot 29 formed in the lower end of the slide shoe 17 whereby when the block is slid in the groove away from the slide shoe the projection 30 will tend to wedge the straddling portions of the latter against the side walls of the groove and effect a friction lock.

For attaining the greatest accuracy in setting the slide, a detachable bracket 31 is formed to embracethe projecting edge 6 and be temporarily secured by means of a set screw 32, and to this bracket is pivoted a cam 33 having a predetermined pitch. The active face .of the cam is graduated and adapted to bear against the slide which is also` provided withk a registering mark i 34. After the slide has vbeen set to-the of the length of the working bar or the radius which may be considered, for example, as ten inches, this being the distance between the movable and fixed centers of movement of the working bar when horizontally disposed. Most devices used as protractors havel theirgraduations within or partly within the outer end of the working bar andare compelled to` use a Vernier or similar arrangement to obtain Vfine readings. It is evident that with the scale of graduations located beyond the arc and tangential thereto a much larger reading can be procured for close adjustment, the proportion being a larger graduation on this device without Vernier than on othersV of the same size with Vernier. It, therefore, obtains that a slight inaccuracy in the setting of the present device decreases toward center while on'the ordinary type of protractor the. error increases in the proportion that the working bar extends beyond the graduations. Keen eyesight is essential with vernierreading whereas by'this tan gential arrangement ofl the scale Vthe distance between lines is increased to ease the close reading. i Y Y The working bar has a long working edge thus especially adapting the tool' for lay-out work. The adjustment is steadied by reason of the working bar being held at each end, as distinguished from the ordinary instrument having the working bar` Sil lla

termined distance apart as by screws 36 whereby, withoutV the usual calculations necessary, the angle to a close reading is at once obtainable. In use as a sine bar the plugs will be used on the work instead of placing the working bar in contact with the work. The plugs, being projected y:from the plane of arm 2, can be placed in contact with a line of work extended indefinitely. A table of tangents may, if desired, be impressed on the base arm 1, such table being or the radius of the instrument and from which the nearest angle to any height within its limits may be given. With the base of the angle known and the height of the tangent, any of the functions of any angle within the circle can be found.

This instrument is preferably constructed from' steel strips and bars so that its manufacture will be facilitated and cheapened. The construction is simple and formed so that the parts may readily be assembled and disassembled assuming that the .scale bar or keeper plate has been graduated to 5', the cam adjustment may then be employed to adjust the Working bar for readings as close as l5".

Having thus described my invention, what I claim as new and desire to secure by Letters Patent isl. A triangle protractor comprising a horizontal arm, a vertical arm connected thereto and formed with a longitudinal groove having an overhanging keeper ledge which is provided With a scale, a slide having a shoe operable in the groove beneath the ledge, said shoe having one end formed with a dovetailed slot, a Wedge lock having a Wedge-shaped projection engaged in the slot and movable relative to the shoe for spreading the latter into frictional contact with the Walls of the groove to secure the` slide in a set position, said slide having a mark registerable with the graduations of the scale, and a Working bar having one end pivoted to the slide and its opposite end slidably connected to the outer end of the horizontal arm.

2. A triangle protractor comprising a horizontal arm, a vertical arm connected thereto, a slide member operably connected to the second arm, a fixed ulcrum on the outer end of the first arm, and a Working bar pivoted to the slide member and having its outer end portion'formed with an edge slot through which the fulcrum extends and slidably and pivotally operates.

3. A triangle protractor comprising a pair of arms iixed at right angular relation, a slide member movably mounted on one arm, fixed fulcrum on the outer end of the other arm, and a Working bar pivoted to the slide and having its outer end formed With a longitudinal edge slot accessible through a lateral entrance opening whereby the ulcrum is insertible bodily into the slot.

4. An instrument of the class described, comprising an arm formed with a groove, having a recessed Wall, a slide member hava part engaged in the groove and formed at one end with a slot, a locking finger pivoted to the opposite end of the slide meniber for engaging in the recessed Wall, and a wedge lock member engaged in the slot and movable relative to the slide member for spreading the slot-ted part into frictional contact With the Walls of the groove.

. 5. A triangle protractor including angularly related arms, a. Working bar slidably and rotatably connected to the outer end of one arm, a slide member mounted on the other arm and pivotally connected to the Working bar, a scale on the latter arm by which the slide may be set to determine the angle of the Working bar, and a detachable supplemental adjusting means coacting with the slide for obtaining Vfiner adjustments than obtainable from the scale and disconnected from said slide to be independent thereof. v

6.' A triangle protractor including right angularly related arms, one having scale graduations thereon, a Working bar movably connected to the Aouter end of one arm and slidably connected to the other arm, and a readily detachable adjusting device mounted on the latter arm and coacting With the slidable connection of the arm with the bar for supplementing the adjustment Voi the latter relative to the scale graduations, said device being independent of the slidable connection and adapted to have only a bearing contact therewith.

7. An instrument of the class described, comprising an arm formed with a groove, a slide member having a part engaged in the groove and formed at one end With a slot, and means operable in the slot to effect Vspreading of the slotted part into locking engagement with the Walls of the groove.

S. An instrument of the class described, comprising an arm formed with a groove, a slide member' having a part engaged in the groove and formed at one end with a dovetailed slot, and a Wedge lock member engaged in the slot and movable relative to the slide member for spreading the slotted part into frictional contact with the walls of the groove.

9. An instrument of the class described, comprising an arm formed with a groove, a slide member having a part engaged in the groove and formed at one end with a dovetailed slot, and means also operable in the groove and movable in the slot to eifect spreading of the slotted part into lockin engagement with the Walls of the groove.

l0. A triangle protractor comprising a horizontal arm, avertical arm connected thereto and formed with alongitudinal groove having an overhanging keeper ledge which is provided with a scale, a slide having a shoe operable in the groove beneath the ledge, said shoev having one end formed with a dove-tailed slot, and a wedge lock having a wedge-shaped projection engaged in the slot and movable relative to the shoe for spreading the latter into frictional contact with the walls of the groove to secure the slide in a set position.

l1. A triangle protractor comprising a horizontal arm, a vertical arm connected thereto and formed with a longitudinal groove having an overhanging keeper ledge, a slide having a shoe operable in the groove beneath the ledge, said shoe having one end formeel with a slot, a locking device movable on the opposite end of the slidemember for engaging beneath the keeper ledge, and a Wedge lock having a part engaged in the slot and movable relative to the shoe for spreading the latter into frictional contact With the Walls of the groove to secure the slide in a set position. e

12. A geometrical instrument including an arm, a Second arm, means connecting the second arm slidably to the firstarm, and a supplemental adjusting device for said means comprising a VU-shaped bracket removably embracing the first arm, and a cam pivotedfon the bracket for bearing on the aforesaid means.

In testimony whereof I have Signed my 15 name to this specification in the presence of two subscribing Witnesses.

JOHN MAGILL.

lVitne-sses JAMES A. MURPHY, W. J GLADU. 

